Guilloché is an engraving technique in which a very precise intricate repetitive patterns or design is mechanically etched into an underlying material with very fine detail. Specifically, it involves a technique of engine turning, called guilloché in French after the French engineer “Guillot�?, who invented a machine “that could scratch fine patterns and designs on metallic surfaces�?.

In modern English, the word guilloche (pronounced ) is used to describe a narrow instance of guilloché : a design, frequently architectural, using two curved bands that interlace in a pattern around a central space. Some dictionaries give only this definition of guilloche, although others include the broader meaning associated with guilloché as a second meaning. Note that, in the original sense, even a straight line can be guilloché, and persons using the French spelling and pronunciation generally intend the broader, original meaning._Wikipedia